Compositions of various types have incorporated within them components or agents which provide a sensation to mucosal membranes and/or to skin. The sensation may be a warming, cooling, relaxation stimulation or refreshing feeling or a combination of two or more feelings. The sensation or feeling may be real or artificial.
Compositions which include a sensation agent include, inter alia, toothpastes, mouthwashes, perfumes, lotions, shaving cream, shampoos, antiperspirants, deodorants, beverages, chewing gum, tobacco products, and pharmaceutical products.
Most compositions known to date, comprising one or more sensation agents, cannot retain the sensation at the site of application thereof in a subject over extended periods of time. Typically, topical formulations do not retain the sensational effect for more than a few seconds. Additionally, the sensation agent may be volatile, such as menthol, used for providing a topical cooling effect, and the formulation may not retain the active agent for more than a few seconds.
The mechanism of cooling and warming sensation or sensation modification for example is poorly understood at present. It has been suggested that, among other options, the action of menthol and other cooling agents and capsaicin, camphor and other heat compounds occurs via “thermoreceptors” that register “cool” and “hot” sensation, respectively. It has been suggested that the ‘cooling’ effect of menthol is a physiological effect due to the direct action of menthol on the nerve endings of the human body responsible for the detection of hot or cold and is not due to latent heat of evaporation such that menthol acts as a direct stimulus on the cold receptors at the nerve endings which, in turn, stimulate the central nervous system.
Substances which are known to provide a sensation of warmth or warmth modulation on application and are called “warming agents” include polyhydric alcohols, capsicum (red pepper) powder, a capsicum tincture, capsicum extract, capsaicin, homocapsaicin, homodihydrocapsaicin, nonanoyl vanillyl amide, nonanoic acid vanillyl ether, vanillyl alcohol alkyl ether derivatives, such as vanillyl ethyl ether, vanillyl butyl ether, vanillyl pentyl ether, and vanillyl hexyl ether, isovanillyl alcohol alkyl ethers, ethylvanillyl alcohol alkyl ethers, veratryl alcohol derivatives, substituted benzyl alcohol derivatives, substituted benzyl alcohol alkyl ethers, vanillin propylene glycol acetal, ethylvanillin propylene glycol acetal, ginger extract, ginger oil, gingeol, and gingeron.
Foams are considered a more convenient vehicle for topical delivery of active agents. There are several types of topical foams, including aqueous foams, such as commonly available shaving foams; hydroalcoholic foams, emulsion-based foams, comprising oil and water components and oleaginous foams, which consist of high oil content, and which are foamable compositions having a specific surfactant selected from the group consisting of ethoxylated lanolin oil, propoxylated lanolin oil, and mixtures thereof and high levels of water that produce fast breaking foams that disappears rapidly into the skin with cooling sensation is described. Some formulations make a sound or crackling effect when foam is dispensed. Dimethyl ether is a substance which evaporates very rapidly and its use with an aqueous non emollient gel composition, lotion composition and a solution in producing a cooling effect (as opposed to mere sensation without cooling). High levels of propellant have also been used to provide a solid or semi ointment deposit with a temperature between minus to plus 5° C.
Foam forming refrigerant compositions, suitable for emergency treatment of burns have also been described.
Foams and, in particular, foam emulsions are complicated systems which do not form under all circumstances. Changes in foam emulsion composition, such as by the addition of active ingredients may destabilize the foam. There is, therefore, a need for a foam composition, which provides desirable properties to the skin and can remain stable whilst accommodating a variety of sensation agents or active ingredients.
Formulations based on oil or ointment or emollients have a number of useful attributes making them suitable candidates for topical pharmaceutical and cosmetic compositions including foamable compositions. They are inherently stable and inert which are clearly desirable characteristics. They are able to moisturize and soften the skin and in appropriate amounts can act as a protective or barrier layer and can form a barrier to water. By appropriate formulation they can act to improve agent delivery to the skin and yet remain resistant to being washed off. On the other hand they are by their nature greasy materials and can be difficult to formulate particularly into a topical foamable composition that can deliver substantially uniform and stable composition or foam that ameliorates or overcomes the look and feel of a greasy material, especially where that composition is waterless or substantially so. It is further a problem to incorporate into such a vehicle, effective amounts of one or more active sensation and/or pharmaceutical ingredients such that they are uniformly present throughout the formulation and are effectively delivered without the use of a lower alcohol in the formulation.
On one level it is far from simple or obvious to produce waterless foamable compositions that when released produce foams of quality suitable for sensation, pharmaceutical or cosmetic application. On a further level having realized a carrier that will produce a waterless foam of quality there is an additional difficulty to be overcome, namely how to adapt the formula and achieve a formulation, which can accept a range of various active sensation, pharmaceutical and cosmetic agents such that the composition and active agent are stable and the foam produced remains of quality. Specifically, one of the challenges in preparing such waterless or substantially waterless foamable compositions is ensuring that the one or more active sensation, pharmaceutical or therapeutic agents does not react, isomerize or otherwise break down to any significant extent during is storage and use. Particularly, there remains an unmet need for improved, easy to use, stable and non-irritating foam formulations, with unique sensation, therapeutic or beneficial properties containing a stable or stabilized active sensation, pharmaceutical or cosmetic agent.
There remains an unmet need for improved, easy to use, stable and non-irritating topical foam formulations containing a stable or stabilized active sensation, pharmaceutical or cosmetic agent having a therapeutic or beneficial effect, intended for treatment of dermal and mucosal tissues.
There is still a need to provide stable aqueous and non-aqueous compositions comprising one or more sensation agents for sustained provision of at least one sensation from the sensation agent(s).